Gene

Electron transport chain

Quantum mechanics

Cell biology

Respiratory chain

Mitochondrial respiratory chain

Biology

Photochemistry

Dihydroorotate dehydrogenase

Electron flow

Cellular respiration

Electron acceptor

Biochemistry

Botany

Respiration

Physics

Mitochondrial DNA

Organic chemistry

Oxygen

Astronomy

Enzyme

Chain (unit)

Mitochondrion

Photosynthesis

Chemistry

Succinate dehydrogenase

Electron

Biophysics

NADH dehydrogenase

Science

Reversing the chain The mitochondrial electron transport chain is a major part of cellular metabolism and plays key roles in both cellular respiration and the synthesis of critical metabolites. Typically, electrons flow through the electron transport chain in a specific direction, ending up with oxygen as the terminal electron acceptor. Spinelli et al . characterized an alternative path of electron flow through the transport chain, ending with fumarate as the electron acceptor (see the Perspective by Baksh and Finley). This pathway operates under conditions of limited oxygen availability, and the authors have confirmed its activity in vivo in a mouse model, observing that the propensity to use this pathway varied between organs. —YN

Fumarate is a terminal electron acceptor in the mammalian electron transport chain